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# -*- coding: utf-8 -*-
# Copyright 2019 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Field handler classes.
The field handlers are meant to parse information from or do some other generic
action for a specific field type for the build_api script.
from __future__ import print_function
import contextlib
import functools
import os
import shutil
import sys
from google.protobuf import message as protobuf_message
from chromite.api.controller import controller_util
from chromite.api.gen.chromiumos import common_pb2
from chromite.lib import cros_logging as logging
from chromite.lib import osutils
assert sys.version_info >= (3, 6), 'This module requires Python 3.6+'
class Error(Exception):
"""Base error class for the module."""
class InvalidResultPathError(Error):
"""Result path is invalid."""
class ChrootHandler(object):
"""Translate a Chroot message to chroot enter arguments and env."""
def __init__(self, clear_field):
self.clear_field = clear_field
def handle(self, message):
"""Parse a message for a chroot field."""
# Find the Chroot field. Search for the field by type to prevent it being
# tied to a naming convention.
for descriptor in message.DESCRIPTOR.fields:
field = getattr(message,
if isinstance(field, common_pb2.Chroot):
chroot = field
if self.clear_field:
return self.parse_chroot(chroot)
return None
def parse_chroot(self, chroot_message):
"""Parse a Chroot message instance."""
return controller_util.ParseChroot(chroot_message)
def handle_chroot(message, clear_field=True):
"""Find and parse the chroot field, returning the Chroot instance.
handler = ChrootHandler(clear_field)
chroot = handler.handle(message)
if chroot:
return chroot
logging.warning('No chroot message found, falling back to defaults.')
return handler.parse_chroot(common_pb2.Chroot())
def handle_goma(message, chroot_path):
"""Find and parse the GomaConfig field, returning the Goma instance."""
for descriptor in message.DESCRIPTOR.fields:
field = getattr(message,
if isinstance(field, common_pb2.GomaConfig):
goma_config = field
return controller_util.ParseGomaConfig(goma_config, chroot_path)
return None
class PathHandler(object):
"""Handles copying a file or directory into or out of the chroot."""
INSIDE = common_pb2.Path.INSIDE
OUTSIDE = common_pb2.Path.OUTSIDE
def __init__(self, field, destination, delete, prefix=None, reset=True):
"""Path handler initialization.
field (common_pb2.Path): The Path message.
destination (str): The destination base path.
delete (bool): Whether the copied file(s) should be deleted on cleanup.
prefix (str|None): A path prefix to remove from the destination path
when moving files inside the chroot, or to add to the source paths when
moving files out of the chroot.
reset (bool): Whether to reset the state on cleanup.
assert isinstance(field, common_pb2.Path)
assert field.path
assert field.location
self.field = field
self.destination = destination
self.prefix = prefix or ''
self.delete = delete
self.tempdir = None
self.reset = reset
# For resetting the state.
self._transferred = False
self._original_message = common_pb2.Path()
def transfer(self, direction):
"""Copy the file or directory to its destination.
direction (int): The direction files are being copied (into or out of
the chroot). Specifying the direction allows avoiding performing
unnecessary copies.
if self._transferred:
assert direction in [self.INSIDE, self.OUTSIDE]
if self.field.location == direction:
# Already in the correct location, nothing to do.
# Create a tempdir for the copied file if we're cleaning it up afterwords.
if self.delete:
self.tempdir = osutils.TempDir(base_dir=self.destination)
destination = self.tempdir.tempdir
destination = self.destination
source = self.field.path
if direction == self.OUTSIDE and self.prefix:
# When we're extracting files, we need /tmp/result to be
# /path/to/chroot/tmp/result.
source = os.path.join(self.prefix, source.lstrip(os.sep))
if os.path.isfile(source):
# File - use the old file name, just copy it into the destination.
dest_path = os.path.join(destination, os.path.basename(source))
copy_fn = shutil.copy
# Directory - just copy everything into the new location.
dest_path = destination
copy_fn = functools.partial(osutils.CopyDirContents, allow_nonempty=True)
logging.debug('Copying %s to %s', source, dest_path)
copy_fn(source, dest_path)
# Clean up the destination path for returning, if applicable.
return_path = dest_path
if direction == self.INSIDE and return_path.startswith(self.prefix):
return_path = return_path[len(self.prefix):]
self.field.path = return_path
self.field.location = direction
self._transferred = True
def cleanup(self):
if self.tempdir:
self.tempdir = None
if self.reset:
class SyncedDirHandler(object):
"""Handler for syncing directories across the chroot boundary."""
def __init__(self, field, destination, prefix):
self.field = field
self.prefix = prefix
self.source = self.field.dir
if not self.source.endswith(os.sep):
self.source += os.sep
self.destination = destination
if not self.destination.endswith(os.sep):
self.destination += os.sep
# For resetting the message later.
self._original_message = common_pb2.SyncedDir()
def _sync(self, src, dest):'Syncing %s to %s', src, dest)
# TODO: This would probably be more efficient with rsync.
osutils.CopyDirContents(src, dest)
def sync_in(self):
"""Sync files from the source directory to the destination directory."""
self._sync(self.source, self.destination)
self.field.dir = '/%s' % os.path.relpath(self.destination, self.prefix)
def sync_out(self):
"""Sync files from the destination directory to the source directory."""
self._sync(self.destination, self.source)
def copy_paths_in(message, destination, delete=True, prefix=None):
"""Context manager function to transfer and cleanup all Path messages.
message (Message): A message whose Path messages should be transferred.
destination (str): The base destination path.
delete (bool): Whether the file(s) should be deleted.
prefix (str|None): A prefix path to remove from the final destination path
in the Path message (i.e. remove the chroot path).
list[PathHandler]: The path handlers.
assert destination
handlers = _extract_handlers(message, destination, prefix, delete=delete,
for handler in handlers:
yield handlers
for handler in handlers:
def sync_dirs(message, destination, prefix):
"""Context manager function to handle SyncedDir messages.
The sync semantics are effectively:
rsync -r --del source/ destination/
* The endpoint runs. *
rsync -r --del destination/ source/
message (Message): A message whose SyncedPath messages should be synced.
destination (str): The destination path.
prefix (str): A prefix path to remove from the final destination path
in the Path message (i.e. remove the chroot path).
list[SyncedDirHandler]: The handlers.
assert destination
handlers = _extract_handlers(message, destination, prefix=prefix,
delete=False, reset=True,
for handler in handlers:
yield handlers
for handler in handlers:
def extract_results(request_message, response_message, chroot):
"""Transfer all response Path messages to the request's ResultPath.
request_message (Message): The request message containing a ResultPath
response_message (Message): The response message whose Path message(s)
are to be transferred.
chroot (chroot_lib.Chroot): The chroot the files are being copied out of.
# Find the ResultPath.
for descriptor in request_message.DESCRIPTOR.fields:
field = getattr(request_message,
if isinstance(field, common_pb2.ResultPath):
result_path_message = field
# No ResultPath to handle.
destination = result_path_message.path.path
handlers = _extract_handlers(response_message, destination, chroot.path,
delete=False, reset=False)
for handler in handlers:
def _extract_handlers(message, destination, prefix, delete=False, reset=False,
field_name=None, message_type=None):
"""Recursive helper for handle_paths to extract Path messages."""
message_type = message_type or common_pb2.Path
is_path_target = message_type is common_pb2.Path
is_synced_target = message_type is common_pb2.SyncedDir
is_message = isinstance(message, protobuf_message.Message)
is_result_path = isinstance(message, common_pb2.ResultPath)
if not is_message or is_result_path:
# Base case: Nothing to handle.
# There's nothing we can do with scalar values.
# Skip ResultPath instances to avoid unnecessary file copying.
return []
elif is_path_target and isinstance(message, common_pb2.Path):
# Base case: Create handler for this message.
if not message.path or not message.location:
logging.debug('Skipping %s; incomplete.', field_name or 'message')
return []
handler = PathHandler(message, destination, delete=delete, prefix=prefix,
return [handler]
elif is_synced_target and isinstance(message, common_pb2.SyncedDir):
if not message.dir:
logging.debug('Skipping %s; no directory given.', field_name or 'message')
return []
handler = SyncedDirHandler(message, destination, prefix)
return [handler]
# Iterate through each field and recurse.
handlers = []
for descriptor in message.DESCRIPTOR.fields:
field = getattr(message,
if field_name:
new_field_name = '%s.%s' % (field_name,
new_field_name =
if isinstance(field, protobuf_message.Message):
# Recurse for nested Paths.
_extract_handlers(field, destination, prefix, delete, reset,
# If it's iterable it may be a repeated field, try each element.
iterator = iter(field)
except TypeError:
# Definitely not a repeated field, just move on.
for element in iterator:
_extract_handlers(element, destination, prefix, delete, reset,
return handlers